Staying too long costs you more than leaving too early ever will.

Leaving too early costs you something you can never measure, which is why it haunts people. Staying too long costs actual months, and the bill stays hidden because every week already spent makes the next one feel cheaper. Sunk time is a weak argument that does a good impression of loyalty.

Ask what you would say to a friend in exactly your situation, in their words rather than yours. Then set a date to look again instead of a decision to make tonight. Naming the date is not the same as leaving, and it stops the question running quietly in the background all term.